A commentary is provided on nomenclatural and taxonomic points arising from Allen and Hannah’s classification of protobranch bivalves (J. Conch. Lond., 32 (1986) pp. 225-249) and an attempt is made to reconcile their classification with one proposed by Scarlato and Starobogatov (Trudy Zoologicheskogo Institute, Akad. Nauk SSSR, 80 (1979) pp.5—38). A number of changes are made to the names and authorship of certain family-group taxa, and several genus-group taxa not considered by Allen and Hannah are discussed. The new sub-family Nuculominae is proposed for those nuculids lacking radial structural elements. Lamellileda Cotton, 1930 is synonymised with Poroleda Hutton, 1893.